The present invention relates to a film growth apparatus. More specifically, the present invention relates to an improved film growth apparatus comprising a plasma source and a steering coil for use in guiding a plasma beam generated by the plasma source into a hearth serving as an anode.
Typical vacuum film growth apparatus using plasma are known as an ion plating apparatus and a plasma CVD apparatus. The known ion plating apparatus includes those using a pressure gradient plasma source or an HCD plasma source which employs arc discharge. Such ion plating apparatus comprises a vacuum chamber, a plasma beam generator (plasma source), a hearth, and a steering coil. The vacuum chamber is equipped with the plasma beam generator and the hearth disposed in the vacuum chamber as an anode. The steering coil is placed outside the vacuum chamber to guide a plasma beam generated by the plasma source into the anode. In the ion plating apparatus of the type described, the plasma beam is generated between the plasma beam generator and the hearth. The plasma beam is guided onto a vaporization material provided on the hearth to heat and evaporate the vaporization material. Evaporated particles of the vaporization material are ionized by the plasma beam. Ionized particles are deposited onto the surface of a substrate supplied with a negative voltage. As a result, a film is formed on the substrate.
The plasma beam generated by the plasma beam generator is guided by the steering coil into the hearth. However, the plasma beam has an electrical current that generates a magnetic field. The magnetic field would cause torsion or bias of the plasma beam.
The torsion or the bias prevents the plasma beam from being directed at right angles with respect to the surface of the vaporization material. As a result, various troubles may occur. For example, the vaporization material may not evaporate uniformly. The plasma density and/or temperature may be varied in a unit space. Thus, any torsion and bias should be corrected. It is known the correction can be achieved by means of adjusting an altitude of the steering coil. However, adjustment of the steering coil requires significant labor because of its large weight.
Therefore, an object of the present invention is to provide a vacuum film growth apparatus that can correct torsion and bias of a plasma beam with a simple structure.
A vacuum film growth apparatus according to the present invention comprises a vacuum chamber, a plasma source attached to the vacuum chamber, an anode placed in the vacuum chamber, and a steering coil provided outside the vacuum chamber to guide a plasma beam generated by the plasma source into the anode. The vacuum film growth apparatus guides the plasma beam to the anode and forms a film onto a substrate.
According to an aspect of the present invention, the vacuum film growth apparatus further comprises a correction mechanism placed on the steering coil or another position between the steering coil and the vacuum chamber where the line of magnetic force from the steering coil is present, to correct bias of the plasma beam.